I just sit down and write without thinking about what to write about beforehand, and I don't even think about how I'm going to incorporate a prompt into a story. My fingers type or my hand writes, and often I'm surprised by what's written. I recognize what I wrote, but somehow I forget how much I wrote. The inspiration doesn't come because I saw or read something and think, "That's a good storyline to write about," but I spin my own version of it.
It depends on what I'm writing about. If it's a comment, then I've read something and want to share my thoughts about it. If it's a movie in which I see something (that others may not see), then those are my thoughts I share, but I can easily wander off because that's how the brain works, and my fingers just keep typing. The only thing that can't keep up with my thoughts is my phone... For as long as I can remember, I have to wait for the words my fingers write to appear on the screen (the good fortune of being able to type quickly, or the bad fortune of a terribly slow device or internet connection). I can imagine how people aren't influenced by others; not everyone reads everything they can find, and I'm definitely not that person anymore. @almaguer has asked me more than once if I knew a particular author or book because my story reminded him of it, and my answer was always NO (who knows, maybe past life experiences?). I also don't consider myself someone with a vivid imagination, even though my brain works overtime and I can write stories while I sleep that I can then write down when I wake up.

I do recognize those many moments (indeed, many) when you're constantly being bothered just as the words are forming and you have the solution... A good reason not to call anyone, to isolate myself. I haven't watched TV for at least 23 years (and no, I don't miss it). I don't talk to my boyfriend every day, and I rarely read books anymore.
Thoughts and impressions will always be there, even though I'm blind (with my eyes closed, I see interesting figures and paintings), deaf, and in solitary confinement. The brain is fascinating enough to spin everything with or without external influence, with or without chemicals, the necessary hormones. Ultimately, you talk to yourself and the stories unfold, and you're in a world only you see.

There will always be an influence somewhere, from within or without, even if it's just that disgusting tube feeding; a little food for thought definitely tastes better.